Vehicle powertrains incorporate an engine, transmission, and a differential drive apparatus. The differential apparatus is, as is well known, a mechanism, which has an input from the vehicle transmission and at least two output members driving the wheels of the vehicle. The vehicle differentials have taken the form of both bevel gear type units and planetary gear type apparatus. Both of these differential apparatus are well known.
The bevel gear type differential generally has a ring and pinion gear input to a carrier or casing, which revolves about the axis of the output side gears. The side gears are driven from the rotary action of the carrier through bevel gears, which are rotatably mounted within the carrier or housing assembly.
Planetary gear differentials generally incorporate a ring gear member, a sun gear member, and a planet carrier assembly member. One of the members, for example a ring gear, is an input member while the carrier and sun gear are output members, which provide drive through the vehicle wheels or other drive mechanisms. The conventional or normal differential within a vehicle drive train does not limit a speed difference, which might occur between the output members of the differential. For example, if one output wheel is on a very slippery surface and the other on a good friction surface, the vehicle wheel on the slippery surface will spin at a high rate of speed while the other wheel is stationary, thus creating a high differential speed across the differential apparatus. This condition, when warranted, is prevented by an apparatus known as a limited slip differential. In such mechanisms, the differential assembly has disposed therein an automatically actuated clutch mechanism, which prevents the rotational difference between the output members and therefore provides a driving force to the wheel on the better drive surface.